As a protection device for reducing the impact to occupants when the automobile is subjected to a frontal collision, an airbag apparatus has been widely diffused. A conventional airbag apparatus is attached in a steering device or an instrument panel provided in front of an occupant. In the case of the conventional airbag apparatus, when the automobile is subjected to a frontal collision, the airbag is inflated at the front side of a driver seat and a front passenger seat to thereby restrain occupants sitting in the driver seat and the front passenger seat from moving to the front side. As a result, the occupants in the driver seat and the front passenger seat are effectively protected at the frontal collision of the automobile.
In recent years, protecting an occupant in an automobile at a side collision of the automobile also has been considered important. Thus, so-called side airbag apparatuses and curtain shield airbag apparatuses have been mounted in vehicles. Specifically, as shown in FIG. 12 for example, at the front passenger seat-side of an automobile 1, a curtain shield airbag apparatus 2 is placed so as to expand at the vicinity of the inner side of the glass at the upper part of a front door 1a. A side airbag apparatus 3 is placed so as to expand at the vicinity of the inner side of the lower part of the front door 1a. In FIG. 12, although the curtain shield airbag apparatus 2 and the side airbag apparatus 3 are shown only at the front passenger seat-side, the curtain shield airbag apparatus 2 and the side airbag apparatus 3 are also provided at the driver seat-side in an actual case.
When another vehicle 4 laterally collides with the automobile 1 as shown by the arrow X in FIG. 12, the curtain shield airbag apparatus 2 and the side airbag apparatus 3 are respectively inflated at a position close to the inner sides of the front door 1a, i.e., an outer region of the front passenger seat, to thereby protect the body of the occupant of the front passenger seat from having a direct contact with the front door 1a. 
On the other hand, Patent Publication 1 discloses an airbag apparatus that is attached in the ceiling of the vehicle interior and that is designed, when the automobile is subjected to a frontal collision, to expand downwardly to the front side of the occupant.
Patent Publication 2 discloses an airbag apparatus that is provided in a console between a driver's seat and a front passenger seat and that is designed to expand, at the side collision of the automobile for example, between the seat back of the driver's seat and the seat back of the front passenger seat.
Patent Publication 3 discloses, for example, an airbag apparatus that is attached in an instrument panel in front of the front passenger seat and that is designed so that the airbag body is expanded at the front side of the occupant of the front passenger seat at the frontal collision of the automobile, a panel member provided in the vicinity of the ceiling is rotated in the lower direction, and a part of the airbag body expanded to the inner side of the vehicle interior is restricted from being moved to the rear side in the vicinity of the ceiling so as to be prevented from being expanded between the head of the occupant and the ceiling.
Patent Publication 4 discloses, for example, an airbag apparatus that is attached in the instrument panel in front of the front passenger seat, that is designed so that the main airbag body divided to left and right parts is caused, at the frontal collision of the automobile, to expand in front of the occupant of the front passenger seat and the ceiling airbag body provided in the vicinity of the ceiling of the front passenger seat is caused to expand in the lower direction and is engaged with a space between the divided left and right parts of the main airbag body expanded to the inner side of the vehicle interior to restrict the dislocation of the main airbag in the lateral direction to thereby prevent the main airbag from expanding in an unexpected direction.    Patent Publication 1: JP2000-185618A    Patent Publication 2: JP2004-217109A    Patent Publication 3: JP2005-067272A    Patent Publication 4: JP2005-145225A